When you use the /give command to get enchanted armor, the command does not give you enchanted armor. It gives you base armor, however there is the enchantment glint on it. My research shows that this is a bug that the website states had been previously resolved, but it is still occuring. It could absolutely be just on my end however, but I'm not sure how that would exactly work.  [^minecraft bug-give command enchants.mkv]

I have included some screenshots of the command I typed in and the result it gave me. This has also happened with other types of armor including golden helmets and chainmail boots. The even stranger thing is I can acquire a stick with knockback on it perfectly fine.